Imagine you owe on five credit cards, you owe five debts. So which debt should you pay first? And the answer is very simple: You should pay the one with the highest interest rate first. But that's not what people do.

It was shocking to realize how many low-income Americans don't have savings accounts.

One percent of people will always be honest and never steal," the locksmith said. "Another one percent will always be dishonest and always try to pick your lock and steal your television. And the rest will be honest as long as the conditions are right - but if they are tempted enough, they'll be dishonest too. Locks won't protect you from the thieves, who can get in your house if they really want to. They will only protect you from the mostly honest people who might be tempted to try your door if it had no lock".

The retail industry has its own headache: it loses $16 billion a year to customers who buy clothes, wear them with the tags tucked in, and return these secondhand clothes for a full refund.

If I gave you now, $10 as a gift, how happy would you be? Would you be happy, is the marginal $10, the best use of $10 you can use? Of course not. If I have you a CD, you know exactly what you are getting and you will have a value for it. So, money has lots of problems with it.

The bad news is that ignoring the performance of people is almost as bad as shredding their effort in front of their eyes. Ignoring gets you a whole way out there. The good news is that by simply looking at something that somebody has done, scanning it and saying "Uh huh," that seems to be quite sufficient to dramatically improve people's motivations.

We can think about how we reduce the pain in paying. So, for example, credit cards are wonderful mechanisms to reduce the pain of paying. If you go to a restaurant and you are paying cash, you would feel much worse than if you were paying with credit card. Why? You know the price, there's no surprise, but if you're paying cash, you feel a bit more guilt.